﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.IO;


class ValidEmail
{
    static void Main(string[] args)
    {
        string emailAdr = @"asdasd@asdasdas.bqg fg@asdasdas.bxxg @asd.bg x@asdqx.bg 
                    / qweasa@asdasdas.qweasd asdasd@qwe.bg \ asdasd@as.dasdasdqQWqweq.eas.bg a@b aaa@bbb @asda.bg";
        Regex email = new Regex(@"\b[a-zA-Z0-9_]+@([a-zA-Z0-9_]+\.)+([a-zA-Z]{2,4})\b");
        var matches = email.Matches(emailAdr);
        foreach (var match in matches)
        {
            Console.WriteLine(match);
        }
    }
}
